1. Field of the Invention
The present invention relates to a paper feeding mechanism for rolled paper which is preferably used in a printing apparatus for recording image information from a personal computer, a facsimile apparatus or the like, for example.
2. Description of the Related Art
FIGS. 3A and 3B are side views of a printing apparatus 31 comprising a prior-art paper feeding mechanism for rolled paper. The printing apparatus 31 includes a body 32 and a cover 33. The cover 33 is placed on the top of the body. The cover 33 is angularly displaced about a pin 34 disposed on the body 32, whereby the cover 33 is opened/closed with respect to the body 32. The pin 34 is provided on an upper portion near one side surface 35 of the body 32 along this side surface. The body 32 comprises a rolled paper storage portion 36, a platen roller 37 and one guide member 38. The cover 33 comprises a printing head 39 and another guide member 40. Paper is carried between the body 32 and the cover 33 from another side surface opposite to the one side surface 35 of the body 32 toward the one side surface 35 near which the pin 34 is dispoed. Therefore, in the body 32, from upstream toward downstream in a paper carrying direction 41, the rolled paper storage portion 36, the platen roller 37 and the one guide member 38 are arranged in this order. In the cover 33, in the same direction, the printing head 39 and the other guide member 40 are arranged in this order.
The rolled paper storage portion 36 is disposed on a lower portion near the other side surface of the body so that rolled paper 42 may be covered with the side surface of the body 32. The printing head 39 and the platen roller 37 are located so that they may be opposite to each other when the cover 33 is closed. The platen roller 37 is used for carrying the paper by its rotation using a friction generated between the platen roller 37 and the paper. The one guide member 38 and the other guide member 40 are located so that they may be opposite to each other when the cover 33 is closed. A carrying path 43 of a relatively narrow space is formed by the one and other guide members 38, 40. The printing apparatus 31 has a structure in which the paper carrying path is provided between the body 32 and the cover 33.
Referring to a side view of the printing apparatus 31 with the cover 33 opened as shown in FIG. 3B, an operation of setting the rolled paper 42 will be described. In the first place, the cover 33 is opened and the rolled paper 42 is placed in the rolled paper storage portion 36 so that it may be pulled out from an upper side along the direction of pulling out the paper. A rolled paper end 44 pulled out for setting is sequentially passed between the platen roller 37 and the printing head 39 and between the one guide member 38 and the other guide member 40, in between the body 32 and the cover 33. Then the cover 33 is closed and the operation of setting the rolled paper 42 is completed.
Referring to a side view of the printing apparatus 31 with the cover 33 closed as shown in FIG. 3A, a printing operation will be described below. Image data and control data such as printing speed are sent to the printing head 39 from an information processing apparatus (not shown) connected to the apparatus. The control data such as rotational speed is sent to the platen roller 37. The printing speed of the printing head 39 and paper carrying speed by the rotation of the platen roller 37 are controlled so that they may be in a mutually optimum condition, whereby a printing is performed. The paper pulled out by the rotation of the platen roller 37 is first printed by the printing head 39, and the paper passes between the printing head 39 and the platen roller 37. Then, a carrying force of the platen roller 37 is applied to the paper and the paper passes through the carrying path 43, so that the paper is discharged from the printing apparatus 31.
In the paper feeding mechanism included in this printing apparatus 31, the one and other guide members 38, 40 are fixed on the body 32 and the cover 33, respectively, and a shape of the paper carrying path 43 is changed by opening/closing the cover 33.
FIGS. 4A and 4B are side views of a printing apparatus 51 comprising another prior-art paper feeding mechanism for rolled paper. The printing apparatus 51 comprises a body 52 and a cover 53. The cover 53 is disposed on the top of the body. The cover 53 is angularly displaced about a pin 54 provided on the body 52, whereby the cover 53 is opened/closed with respect to the body 52. The body 52 comprises a rolled paper storage portion 55 and a printing head 56. The cover 53 comprises a platen roller 57 and a guide path 58. The rolled paper storage portion 55 partially protrudes from one side surface 59 of the body. This protruding portion 60 is used for disposing the pin 54. Specifically, in a portion in which the protruding portion 60 of a housing of the body 52 and a housing of the cover 53 overlap each other the two pins 54 are arranged so that only the housings may be connected. Therefore, this has no influence on the accommodation or operation of rolled paper 61. The printing head 56 is disposed near another side surface opposite to the one side surface 59 near which the rolled paper storage portion 55 is mounted. The printing head 56 and the platen roller 57 are located so that they may be opposite to each other when the cover 53 is closed. A relatively narrow guide path 58 of constant width is provided from the platen roller 57 toward a cover upper surface 62 so that it may be inclined toward a position in which the rolled paper is set.
Referring to a side view of the printing apparatus 51 with the cover 53 opened as shown in FIG. 4B, an operation of setting the rolled paper 61 will be described below. In the first place, the cover 53 is opened and the rolled paper 61 is placed in the rolled paper storage portion 55 so that it may be pulled out from a lower side along the direction of pulling out the paper. In order that the paper is passed between the printing head 56 and the platen roller 57, a pulled-out rolled paper end 63 passes along a side surface 64 opposite to the pin 54 of the platen roller 57, and the rolled paper end 63 is inserted into the guide path 58. Then, the cover 53 is closed and the operation of setting the rolled paper 61 is completed.
Referring to a side view of the printing apparatus 51 with the cover 53 closed as shown in FIG. 4A, a printing operation will be described below. In the same manner as the prior art shown in FIGS. 3A and 3B, image data and control data such as printing speed from an information processing apparatus (not shown) are sent to the printing head 56. The control data such as rotational speed is sent to the platen roller 57. The printing speed of the printing head 56 and the rolled paper carrying speed of the platen roller 57 are controlled so that they may be in a mutual optimum condition, whereby the printing is performed. After leaving a printing section, the rolled paper 61 passes through the narrow guide path 58 disposed in the cover 53, and is discharged from the printing apparatus 51.
In the paper feeding mechanism provided in this printing apparatus 51, since the guide path 58 is provided in the cover 53, a shape of the guide path 58 is not changed even during the printing operation and the operation of setting the paper.
In the paper feeding mechanism for rolled paper, when the guide members of the carrying path are separately arranged in the body and the cover, the shape of the carrying path is changed by opening the cover to set the paper. For example, In the case where a relatively acute-angled portion is formed, the rolled paper end is caught on the side surface of the carrying path, and thus smooth insertion of the paper is difficult. More specifically, since the rolled paper is curled when it is pulled out, the paper is considerably caught depending on relationship between the orientation of the angled portion and the orientation of curl of the rolled paper to be carried, and thus the smooth insertion of the paper is extremely difficult. Also, in the case where the carrying path is too wide, the paper is bent due to reduced paper tension, and thus the paper is prone to be caught and jammed in the carrying path.